The present invention is generally related to shaft seals and, more particularly, to a sealing assembly for rotatable shafts. Specifically, the present invention is directed to maintaining a rotatable seal member in engagement with a stationary seal member by utilizing a rotatable seal collar. In various types of machinery, it is continuously a problem to seal the opening through which a rotatable shaft protrudes. The problem is manifested in the difficulty of preventing leakage or loss of pressure or loss of vacuum while at the same time avoiding undue shaft friction. The shaft friction can generate heat, cause loss of power, and even damage the machinery. One method of effecting a seal at a joint between a stationary element and a rotatable shaft has been through the use of packing, stuffing, or the like. However, packing or stuffing causes considerable friction on the shaft. Another method of effecting a seal has been to utilize O-rings. However, O-rings have presented a problem due to the difficulty of providing a proper material to accommodate the wear thereon when utilized with shafts that operate at high speed. The shaft seals have also for the most part required the machinery to be stripped or dismantled for replacement purposes. The necessity for stripping or dismantling the machinery is most undesireable particularly where the machinery being sealed is large and heavy. Moreover, in order to replace conventional mechanical seals, the machinery must often times be shut down for prolonged periods of time resulting in enormous losses in productivity.
As a result, it has been recognized as desirable to provide the parts of a mechanical seal which are subject to wear in split fashion so that they can be easily mounted and later disassembled for repair or replacement purposes. This was successfully accomplished in my earlier U.S. Pat. No. 4,215,870 issued on Aug. 5, 1980, and in my earlier co-pending patent application U.S. Ser. No. 363,375 filed on Mar. 29, 1982, and seals manufactured according to my patent and patent application have been installed and proven to be highly effective not only in terms of their sealing capabilities but also in terms of their drastic reduction in down time of expensive machinery used in costly processes. With the features of the inventions of my earlier patent and patent application, a split-type seal has been provided which can be easily assembled and disassembled relative to machinery without interferring with the positioning or mounting of the stationary element and the rotatable shaft associated with it.
With attempts prior to my earlier patent and patent application to provide a split-type seal, it had been a problem to maintain a complete seal at all times completely about the rotatable shaft. During operation, the seals could easily become worn or deteriorated and the wear and deterioration could be non-uniform circumferentially about the shaft because of a number of reasons such as misalignment of the shaft with respect to the machinery with which it is used, or due to other factors. However, I was able to provide a sealing assembly which overcame the problem of non-uniform wearing or deterioration of the seal parts.
As set forth in my earlier co-pending patent application U.S. Ser. No. 363,375, I later became aware of still additional problems requiring a solution. For instance, sealing assemblies are often times needed in emergency situations. This is particularly true in applications which advantageously utilize the rotatable shaft seal disclosed and claimed in my earlier U.S. Pat. No. 4,215,870 where a seal is quickly needed on machinery used, for instance, in dangerous manufacturing process such as the grinding of caustic chemicals and the like where time is of the essence and the seal must be made available in the field on extremely short notice. However, the shafts of such machinery very significantly in size. Since time is of the essence in these applications, and it is not feasible to custom order a split seal from the manufacture, field service personnel have been required to stock a large variety of seals in order to be able to service a customer on a timely basis.
In my earlier patent application, I successfully overcame these problems with a unique sealing assembly, kit and method for rotatable shafts. This was done by providing a separate inserted adapted to be mounted in an insert-receiving opening in the stationary seal member wherein a shaft-receiving opening in the insert is initially dimensioned so as to be smaller than a rotatable shaft and is thereafter adapted to be enlarged in the field before use so as to generally conform to the rotatable shaft. With this arrangement, the sealing assembly is uniquely suited to be selectively supplied in kit form.
Despite the significant advances offered by my earlier patent and patent application, I have become aware of still other problems with shaft seals. In particular, and in high pressure environments, there can be a tendency for leakage resulting from a slight separation of the rotatable seal member from the stationary seal member since fluid under pressure has a tendency to overcome the frictional grip of the rotatable seal member on the rotatable shaft to thereby cause the rotatable seal member to slip on the shaft. While leakage is undesirable in any situation, it is entirely unacceptable in numerous applications where dangerous materials are involved.
The present invention is directed to solving the above and other problems while enhancing the effectiveness and versitility of the seals described in my earlier U.S. Pat. No. 4,215,870 and co-pending patent application U.S. Ser. No. 363,375.